The invention relates to a molding or casting process, and more particularly to a process for inserting a foam mold pattern into a mold flask, and for compacting sand about the foam mold pattern.
In a lost foam casting process, the mold pattern which forms the desired molding cavity in the sand is a foam mold pattern that vaporizes when contacted by molten metal so that it need not be removed from the sand before casting. Since it is not necessary to remove the foam mold pattern from the sand before casting, the mold flask need not be separable into two parts, the cope and the drag, and the mold pattern can have a more complicated configuration than with conventional cope and drag flasks.
A lost foam casting process includes the steps of placing the foam mold pattern in the mold flask, compacting sand around the mold pattern, and pouring molten metal into the foam mold pattern. The molten metal causes the foam mold pattern to vaporize, and when the metal cools, the casting is removed from the sand.
Because the sand must be tightly compacted around the mold pattern in the flask, and because of the complicated mold pattern configurations permissible with a lost foam casting process, it is desirable to have a process which will compact the sand around the mold pattern to high sand pressure.
Prior processes for compacting sand around a foam mold pattern in a mold flask include the step of filling the mold flask with sand before vibrating the sand to compact it around the mold pattern.
Prior processes also include the steps of depositing sand into the mold flask through tubes extending downwardly into the mold flask, and shaking the mold flask with vertical vibrational forces while filling the mold flask with sand.
Attention is directed to the following U.S. Pat. Nos. which relate to the field of the present invention.
______________________________________ Patentee U.S. Pat. No. Issued ______________________________________ Yonemitsu 4,181,171 Jan. 1, 1980 Johnston 3,007,216 Nov. 7, 1961 Taccone 2,988,789 June 20, 1961 Moran et al. 2,893,079 July 7, 1959 Dupre 1,962,734 June 12, 1934 Heller 1,113,626 October 13, 1914 MacDonald 1,127,471 February 9, 1915 ______________________________________